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Triggering and Luminosity Scenarios

Exploring the triggering and luminosity scenarios in high-energy particle physics, focusing on the ATLAS Trigger system levels and features. Discusses rate limitations, luminosity scenarios, nomenclature, trigger menus, and additional triggers for physics, calibration, and monitoring purposes.

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Triggering and Luminosity Scenarios

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  1. Triggering and Luminosity Scenarios Maris Abolins Michigan State University Midwest Physics Group University of Indiana

  2. The ATLAS Trigger • Three Level Trigger • Lvl1 - Hardware • Lvl2 - Regions of Interest + Processors • Lvl3 - Processor Farm • Lvl2 + Lvl3 = HLT(High Level Trigger)

  3. Features • Lvl1 Trigger • Calorimeter • electromagnetic - cluster with hadronic veto • jet trigger - hadronic cluster & window algorithm • particle trigger - jet trigger with isolation •  system • HLT Trigger - Data available at full readout resolution

  4. Rate Limitations on Lvl1 • 75 kHz upper limit due to front end electronics ->100 kHz with deadtime • ~44 kHz with safety factor due to uncertainty in rates • ~25 kHz with cost-driven deferrals of system components • ~10 kHz with deferrals and safety factor

  5. Rate Limitations on HLT • HLT/DAQ TP (2000) ~540 Hz to storage • New Guidelines ~200 Hz to storage due to offline computing considerations

  6. Luminosity Scenarios • ATLAS Level1 TDR • L~1x1033 cm-2 s-1 for first year of operationLow luminosity - b-physics program • L~1x1034 cm-2 s-1 thereafterHigh luminosity - discovery physics • Post 2001 - Initial L~2x1033 cm-2 s-1

  7. Nomenclature • Lvl1 - Capital letters • HLT - small letters • Isolation -> I • E -> ET • J -> Jet • xE -> Missing ET • Number in front indicates no. of objects e.g. 2J55 is 2 jets with ET > 55 GeV at Lvl1 • 2em15i is 2 isolated em deposits with ET>15 GeV in HLT

  8. Lvl1 Rates (from F. Gianotti before the LHCC on 2-Oct-2002)

  9. Lvl1 Rates Continued

  10. Things to note • Rates are dominated by single  and e • To reduce rates these thresholds must be raised • Light Higgs is impacted and B physics program is jeopardized • Monitoring and calibration triggers ~10 - 20%. CDF & DØ Run II are higher~30%

  11. General Physics Trigger Menu for L=2x1033from T. Schorner-Sadenius and S. Tapproge, ATL-DAQ-2003-004

  12. More but rates uncertain

  13. Additional Triggers • High priority, unprescaled, discovery potential, minimal additions to rate • Most prominent at Lvl1: EM30,40,50,60 and 2EM30 with partly relaxed isolation criteria • Additional Jet, Energy and  triggers are under study

  14. Prescaled Physics, Calibration and Monitoring Triggers • Extend physics measurements to lower ET, for example • Calibrate efficiency of more restrictive triggers • Calibration triggers for energy scale, J/,.Z->ee,,W->jj etc. • Minimum bias triggers • Monitor triggers for luminosity, vertex position • This subject is just starting to be addressed

  15. Conclusions • Trigger Menus exist for most likely scenarios at beginning of run • Absolute rate estimates are thought to be known within a factor of 2. There are uncertainties due to QCD processes and machine backgrounds • Work on Monitoring and Calibration Triggers is just starting

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